Drive pulley for buttonhole stitching machines



July 23, 1935. G. MINKOWITZ 2,008,872

DRIVE PULLEY FOR BUTTONHCLE STITCHING MACHINES Filed Feb. 6, 1955 ,ffgilarsem hko w INVQNTOR' Patented July 23, 1935 were: l

DRIVE PULLEY Fon iiiJTToN'HoLE STITCHING MACHINES George'Minkowitm New York, N. Y. I Application February 6, 1935, Serial N6. 5,16 8 ,3 Claims. (dim- 567 I This invention relates generallyto buttonhole stitching machines and has reference particularly to improvements in a cushioning device in-v corporated in the drivenorfast. pulley of the machine to soften or cushion the impactof the stopping operation. 1

My invention is a further development of the bufiing spring arrangement fully described in United States Letters Patent-No. 541,276

Buttonhole stitching machines; operate at a considerable speed and in order to bring the stitchingmechanismsto an absolute rest at thecompletion of a certain number of stitches, a

stop motion device of the general type shown in United States Letters Patent No. 743,213, has been devised and cooperates with the driven pulley .to arrest movement thereof onthe com pletion oi-the buttonhole. The impact created I by the sudden stopping of parts operating at so great a speed, must be cushioned and this has been -done heretofore by a yicldable connection between the fast pulley and a cam which receives the stop motion device, the connection being a buffer spring which is actually an arcuately shaped helical metal member, and which as a consequence is subject to all of the disadvantages inherent in metal springs, i. e., crystallization of the material and breakage in the cells when subjected to sudden and severe strains. In factories where large numbers of these buttonhole stitching machines are in use, a staff of mechanics isconstantly in attendance to make replacements of broken springs, so many of them being fractured during the course of operations Not only is a machinetemporarily out of commission while a replacement of the spring is being made, but one or more extra stitches may have been taken by the machine in its failure to stop due to the broken spring and as a result the buttonhole is likely to be imperfect. Up to the present time no suitable substitute for the buffer spring has been discovered and the users of this type of machine have been obliged to content themselves with replacements in order to keep the machines in operation.

The present invention is contemplated to overcome the difficulty outlined above and has for its object to provide rubber or other suitable cushioning members as a substitute for the more or less fragile bufier springs originally used in these machines.

A further object of this invention is the use of a suitable balance medium embodied in the driven pulley, whereby off-center weight carried by the main shaft is maintained in balance.

1 I accomplish thesefobjects by means of the embodiment of my :invention hereinafter describediset forth inthe claims andillustratively exemplified in' the accompanying drawing, in which, I Figure. 1 is a side elevational view ofv a button hole. stitching machine embodying my improved cushioning device, r t i:

Figure 2 is an elevational View. of the face of a driven fpulley'with atportiortof the cover plate 10 broken'away; I 1 I Figure '13 is a substantially longitudinal sectionalviewof'the, pulley takenon -lines-3-3 of F urw; an

Figure 4 is another sectional view takenon -lines,4-4 of Figure 2.

Referring to the dr'awing,,the buttonhole stitching, machine comprises-abed Hi from the rear end of which. rises the standard I] ofvthe brackfe't arm I 2 'terminatingfin a head I3. A re'cipro catin'gliand verticalgneedlebar and needle. I 4 are jou'rnaledintlie head I3 and receive movement from the wellknown needle jogging mechanism, not shown.

The needle operating mechanism comprises a main shaft I5 journaled within and longitudinally of the bracket arm I2 and projected from the rear end thereof to receive a cam I6 rotating with j a driven pulley I1 fast on theshaft I5. Adjacent to this fast pulley I1 is a loose pulley I8.

The stop motion device of the present machine comprises a lever I9 pivotally mounted on a center screw 20 tapped in ears 2| on the arm I2 of the machine, said lever carrying a vertically movable rod or plunger. 22 cooperating with the cam I6. The rod 22 is pressed upwards and the upper end is fitted to enter a peripheral notch 23 formed in the cam I6 which, as hereinafter described, is yieldably connected with the fast pulley Il so as to soften or cushion the impact of the stopping motion.

The cam I6 is provided with a hub 24, which fits over a sleeve 25 projecting from the outer wall of the fast pulley I I and which forms part of the sleeve embracing the main shaft I 5. The cam I6 rests against the wall of the pulley I1 and carries a crank pin 26' which is axially disposed with respect to the axis of the cam and which enters a concentric arcuate slot 21 in the adjacent wall of the pulley.

The pulley I1 comprises a hollow wheel having an external peripheral belt groove 28, center hub 29 projecting from the closed end or wall and having a bore 30 projecting through the peripheral wall of the pulley is of substantial thickness and is cut away at its outer end to form a shoulder 31 defined by a slight flange forming one side of the belt groove 28. A plate 32 seats in the open end of the pulley against the shoulder 3| and is provided with a center opening to embrace the end of the hub 29, the plate being fixed in closed position by screws driven into the shoulder. The pulley I! is fixed to the shaft l by means of a pin 33 which is driven through transverse openings in the shaft l5 and hub 29.

The annular space or chamber inside the pulley is occupied by an arcuate metal block 34 which provides the necessary balance because of its own weight and that of a plurality of lead plugs 35 embedded therein, and which is anchored in the pulley shell by means of two or more pins 36,

each of which is carried in a bore 31 drilled to embrace the adjacent walls of the shoulder and block 34.

The block 34 occupies substantially one half of the annular chamber in the pulley shell and the other half embraces the arcuate slot 21 and accommodates a loosely disposed arcuate shaped block piston 38 which is provided with an orifice 39 adjacent one end to receive the crank pin 26 of the cam H5. The block 38 occupies sub stantially one half the space between the ends of the fixed block 34 and is arranged on the pin 25 so as to bring it normally about midway of the space. Arranged in the spaces between the ends of the two blocks'are buffer blocks of rubber 49, which fill the spaces and which take up and absorb the impact of the stopping operation of the machine. v

In the operation of thedevice the parts will function, as fully described in United States Letters Patent No. 541,276, the rubber blocks 40 taking the place of the buffer spring of the earlier construction. It has been found in practice that the rubber blocks 40 will absorb the impact of the stopping operation much more effectively than was ever possible with metal springs and after long use will be still in perfect condition, thus the necessity of replacements is almost completely eliminated and the speed of machines operating with the present invention may be increased beyond anything possible in the original machines. It is also pointed out that all existing machines of this character may be equipped with the present, invention'by merely substituting the latter for the pulley originally supplied with the the device.

Having now described my invention and the manner in which the same operates, what I claim and desire to secure by Letters'Patent is:

- 1. A pulley and cam for the stop-motion device of a buttonhole stitching machine, comprising a shell having a closed end and a peripheral belt groove and provided with an annular chamber inside said shell and a block counterweight fixed in the chamber, a block piston connected to the cam and movable in the annular chamber between the ends of the fixed block, and rubber cushion block's interposed between adjacent ends of the fixed block and block piston to soften the impact of the stopping operation.

Y 2. Apulley'as claimed in claim 2, including a cover plate attachable to the open side of the shell and disposed over the said blocks.

3. A pulley and cam for the stop-motion device of a buttonhole stitching machine, comprising a shell having a closed end provided with an arcuate slot, a peripheral belt groove and an inner semi-annular chamber, a piston block movable in said chamber and connected to said cam through the arcuate slot, and a cushion block filling the space between the end of the piston block and adjacent the end of the semi-annular chamber to soften the impact of the stopping opera tion.

' i GEORGE MINKOWITZ. 

